Today, LED backlighting is more and more widely adopted by monitors. For example, in LCD TV field, LED is tending to replace traditional CCFL as the backlighting source. In some applications, besides currents provided to LED strings, voltages are also provided to the other circuits or chips inside the whole system, e.g., MCU by a LED driver. A driver in these applications often adopts single power stage multiple outputs topology, to provide multiple outputs, e.g., currents to the LED strings and voltages to the other circuits.
In a single power stage multiple outputs topology, one of the outputs is in a feedback loop to control the power conversion of the single power stage. Compared with other output regulation loops, the feedback loop with power conversion control is slow, especially when any one of the other outputs suffers a sudden load change, the feedback loop with power conversion control may need a long time to respond, which results in a slow load regulation. In other words, the dynamic response of the driver is poor.